|  |  | Overview
In the "LAN Design" chapter you learned about LAN design goals and methodology. In addition, you learned about design considerations related to Layers 1, 2, and 3 of the Open System Interconnection (OSI) reference model. Reliability, connectivity, ease of use, ease of modification, and ease of implementation are other issues that need to be considered in building networks: To be reliable, a network must provide a means for error detection as well as the capability to correct the error. To provide connectivity, a network must be able to incorporate a variety of hardware and software products in such a way that they can function together. To be easy to use, a network must perform in such a way that users need to have no concern for or knowledge of the network's structure or implementation. To be easy to modify, a network must allow itself to evolve and adapt as needs change or expand, or as new technologies emerge. Finally, to be easy to implement, a network must follow industry-wide networking standards, and it must allow for a variety of configurations that meet network users' needs. In this chapter, you will learn how the use of routers can help you address these issues. In addition, this chapter discusses how routers can be used to connect two or more networks and how they are used to pass data packets between networks based on network protocol information. You will also learn that a router can have more than one Internet Protocol (IP) address because it is attached to more than one network. An important function of routers is to examine incoming data packets and make path selections based on information stored in their routing tables. In this chapter, you will learn more about how routers operate and what kinds of protocols they use. Finally, this chapter describes routing and IP routing protocols and discusses Cisco's proprietary implementation of Interior Gateway Routing Protocol (IGRP).
| Threaded Case Study
Washington Project: Routing Protocols and Implementing IGRP
The concepts covered in this chapter will help you understand routing protocols. Routing protocols (such as IGRP) route routed (routable) protocols (such as IP and IPX) through a network. This chapter will help you apply IGRP to the network design you have been creating for the Washington School District project. In addition, you will learn how to implement IGRP and all the IGRP-required configurations needed for the network implementations.